package _3_TwoPointers;

import _2_Linkedlist.ListNode;

public class A25_mergeTwoLists {
    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
        ListNode dum = new ListNode(0),cur = dum;
        while(l1 !=null && l2 != null){
            if (l1.val >= l2.val){
                cur.next = l2;
                l2 = l2.next;
            }else if (l1.val < l2.val){
                cur.next = l1;
                l1 = l1.next;
            }
            cur = cur.next;
        }
        cur.next = l1 != null ? l1 : l2;
        return dum.next;
    }
    public ListNode mergeTwoLists2(ListNode l1, ListNode l2) {
        StringBuilder S = new StringBuilder();
        if (l1 == null) {
            return l2;
        } else if (l2 == null) {
            return l1;
        } else if (l1.val < l2.val) {
            l1.next = mergeTwoLists(l1.next, l2);
            return l1;
        } else {
            l2.next = mergeTwoLists(l1, l2.next);
            return l2;
        }
    }

}
